It is a common practice to provide furrows for irrigation and/or drainage between beds of agricultural crops or trees for the delivery and/or removal of water. In the cultivation of citrus crops, for example, furrows in the form of shallow angle V-shaped channels are used to drain the beds of adjacent rows of trees in the rainy season. During the winter months, the same furrows are often flooded with water to protect the crops from freeze or frost damage.
Such furrows become clogged with weeds, earth runoff and debris after a period of time and must be cleaned and reshaped. In addition to natural erosion, agricultural equipment, such as pickers and the like, traveling through the furrows leads to their deterioration. Cleaning and reshaping is necessary to permit the free flow of water in the furrow.
Furrows to which the invention relates differ from ditches in that the width-to-depth ratio of the furrows is much greater. The furrows also have considerably shallower wall angles of between 0.degree. -30.degree.from horizontal, whereas the wall angles of ditches are normally on the order of 60.degree., or more.
A typical furrow arrangement of the type to which the present invention relates is found in citrus groves in South Florida, wherein water furrows are formed in the spacing between single- or double-row beds of citrus trees. Spacing between adjacent trees of neighboring beds is about 30' from trunk to trunk, with a 6' growth allowance made for the foliage canopy drip line. The furrow width is thus about 18', with side walls sloping at an angle of about 10.degree. from horizontal, with 5.degree. to 10.degree. angle slopes being usual and 15.degree. slopes being less common. Natural erosion and equipment tire rut damage disturbs the angle and fills in the furrow bottoms to disrupt lateral water flow. Also, while grass growth is encouraged to withstand wall erosion, weed invasion and overgrowth tends to clog the runoff channels. The result is that the furrows must be mowed about five to six times per year and should be cleaned out and reshaped about once each year. Because of cost and other drawbacks of conventional refurbishing techiques, however, cleaning and reshaping is typically performed only once every three to five years.
Conventional methods employed to clean and reshape the furrows include the use of agricultural plows, discs, blades, and in some locations, road graders. These implements cannot be used when the furrow is wet or has water standing in it. In a typical prior art process, the furrow is first mowed and then tilled to break up the root structure of the sod covering. Discing is then performed to cut transversely into the soil in order to shape out a trench in the furrow bottom leaving a berm partway up each furrow wall. Multiple passes are then made with a blade to displace the berms up the walls toward the tree beds to prevent the relocated soil from washing back down.
Such a process has many disadvantages. The use of different implements in a combination of operations requires several passes over the same ground to achieve proper cleaning and reshaping. This takes time and labor and, consequently, costs money. Transverse cutting during tilling, removes the wall retaining root structure, leaving the furrow unprotected until it can be replaced. The use of plows or blades forms the soil and vegetation into clods that must then be disintegrated and dispersed, usually by a disc. When a disc is used, the soil is left soft and fluffy and, therefore, exceptionally prone to erosion should a heavy rain occur. The upward displacement of the berm, leaves a ridge of soil at the top on both sides of the furrow. This results in undesirable water retention and erosion at the beds. These ridges also cause difficulty in mowing at a later date.
It is desirable to apply a herbicide for weed control immediately after cleaning and reshaping, and also to apply seed and other chemicals to stimulate the growth of the soil retaining sod covering. However, due to the disturbed condition of the soil, this cannot normally be accomplished at once, and a waiting period of one to several weeks is normally necessary before the necessary equipment can be moved through the furrow.
Special V-deck mowers are available for mowing the shallow angle furrows in a single pass. The Vee.TM. mower available from Orange Service Company, Clermont, Fla., for example, operates off a tractor power take-off (PTO) and has two rotors with adjustable 0.degree.-30.degree. angles (one for each wall), and has a cutting width of 10' to 12' and a cutting height of 2" to 8". Equipment for refurbishing the furrows in one pass is, however, not available.
Ditchers, such as the doublewheel and monodoublewheel models of Dondi ditchers (available from Impex International, Spartanburg, S.C.) which cut two slopes in one pass of a ditch, are not suitable for cutting shallow angle furrows. The rotating drums of such ditchers are rotated about generally horizontal axes for cutting transversely, almost vertically, into the soil with a perpendicular cut. The width of the cut is too small relative to the depth of the cut, and the resulting ditch wall angles are too steep. The transverse cut destroys the root system of the erosion retarding, soil retention vegetation layer and the cutters cause undesirable balling and rolling of the severed soil and vegetation. Such devices are mounted on tractor three-point lift assemblies which makes them react too abruptly to ground elevation changes for even cutting. The ditchers are, moreover, not angularly adjustable.